This invention relates to a surgical instrument or tool used for inserting a synthetic, intraocular lens, in folded condition, through a small incision in the limbus, into the anterior chamber of an eye.
In the surgical replacement of a defective natural lens with a synthetic lens, an incision is made in the limbus or margin of the cornea of the eye. The defective, natural lens is surgically removed through the incision, leaving the natural lens capsule within the eye. Thereafter, a synthetic lens is inserted through the incision into the anterior chamber of the eye. Then, the synthetic lens is positioned in the place of the natural lens, using a surgical instrument extending through the incision. Upon completion of the surgical procedure for positioning and holding the lens in proper position, the incision is closed with sutures and is allowed to heal.
The removal of the natural lens requires only a very small incision because the lens is emulsified with an ultrasonic probe and sucked out. However, in the past, the synthetic replacement lens, which was normally made of a rigid plastic material of a size and shape to replace the natural lens. Thus, a substantial-sized incision was required to insert the rigid lens into the anterior chamber of the eye, beneath the cornea, for subsequent positioning into the sulcus or capsule. For example, an incision on the order of roughly 12 millimeters or more was required.
More recently, a resiliently flexible or foldable synthetic plastic lens has been developed for use, instead of a rigid lens, as a replacement for the natural lens. Such foldable lens may be rolled or folded so that it can be inserted into the anterior chamber through a much smaller incision than that previously required for the rigid lens. By way of example, an incision of about 3.5-4 millimeters is adequate for insertion of the rolled or folded lens. Once the folded lens is inserted into the eye chamber, it resiliently returns to it normal, unfolded shape.
There is a substantial advantage in reducing the length of the incision in this type of eye surgery. Specifically, the smaller the incision, the less the induced astigmatism caused by the operation, the faster the wound heals, the less bleeding is encountered and there is less intraocular inflammation. With the smaller incision, the number of sutures can be reduced to the point where one or two sutures may be adequate for closing the wound. This is a substantial advantage over the previously-needed multiple sutures. Thus, there is a considerable advantage in using a foldable lens in place of the earlier, rigid synthetic lens.
However, the folding and holding of the folded lens and, particularly, the release of the folded lens from a surgical insertion tool utilized in positioning the lens has frequently caused damage to the delicate lens itself and to the tissues fo the eye. The more delicate or thinner marginal edges of the lens are especially vulnerable to damage. Attempts have been made to provide instruments or tools which can hold a folded lens during insertion and can release the lens within the anterior chamber of the eye without damaging or scratching the lens. However, presently available tools are unable to avoid damage to an inserted lens at all times. Consequently, the invention herein relates to a surgical instrument or tool which enables easy folding of a lens into the tool, which holds and permits insertion of the lens into the eye chamber, and which releases the lens without damage to the lens.